1. Field of the Invention
This invention relates generally to filters for removing particles from air flowing through the filter.
2. Description of the Related Art
Conventional air filters utilize pleated or flat sheet filter media that filters the air by forcing the air through extremely small pores formed between fibers in the sheet media. By thus “straining” particles from the air, the air is cleaned and the filter retains the particles. Such filters have a substantial pressure drop across the filter, and a powerful motor is required to force the air through the filter. Furthermore, pressure drop increases as particles are filtered, because the filtered particles prevent air from flowing through the openings in the filter.
Some air filters are pleated to increase the amount of surface area available for particles to be collected in to reduce the increase in pressure drop. Pleating extends the surface so it becomes permeable at an acceptable pressure drop. However, this merely postpones the inevitable clogging of the filter with particles. Pleated material is generally sealed to a filter frame with hot melt, polyurethane or cold glue, and the processing and material costs with such filters are substantial. Sealing is necessary because any large openings in or around the filter tend to allow a disproportionate amount of air to pass through, thereby defeating the filter media's ability to strain particles.
Some air filters are manufactured with filter media that is electrostatically charged in order to attract particles in the air to the media. For such filters the main transport mechanism of particles to the media fibers is through collision, diffusion and electrostatic attraction rather than by forcing air through a pore that is smaller than the particle. However, such materials have substantial pressure drops, and are costly and are relatively incapable of being adapted to various applications.
The need exists for a low cost air filter that is capable of being adapted to various circumstances.